Certain medicaments and other materials are comprised of components that are incompatible with one another as a previously prepared mixture, and accordingly, must be mixed just prior to dispensing. For example, emulsifying needles have been provided with a single tubular passageway with a socket at each end for connection between a pair of syringes carrying the separate components. One example of incompatible components includes, for example, an oil and an aqueous solution prepared on demand to form an emulsion having a relatively short shelf life at room temperature. The components may be considered to be “incompatible” with one another for a variety of reasons. For example, certain emulsified mixtures used in the health care field become unstable upon mixing, with the resulting mixture having a limited shelf life not suitable for storage, or for practical, commercial distribution. Instability may arise due to chemical reactions as well as interactions that do not involve chemical bonds. Accordingly, practical applications of such materials require devices and systems to prepare mixtures of components which must be stored separately until the time of application or use, or stored at a relatively lower temperature, for example by refrigeration, prior to use.
Emulsifying needles have been proposed for mixing two components (e.g. oil and water or other aqueous solution) carried in their own respective general purpose syringes. Typically, the contents of one syringe are passed through the emulsifying needle to the other syringe to contact its contents. The receiving syringe is then pumped to move the components in a reverse direction through the emulsifying needle to the now empty syringe. Successive iterations of the pumping operations are carried out until the desired mixture condition is reached. For example, one common mixture condition is the emulsification of the two components. Other types of mixtures other than emulsifications may be prepared in a similar manner. Mixing arrangements employing an emulsification needle and general purpose syringes may be unsuitable for certain applications, as where a disposable mixing device is preferred.
As will be appreciated by those skilled in the art, the components frequently have substantially different viscosities and other physical properties either in their separate stored state or when combined in a mixture, so as to require substantial pressures to be developed by the syringes, when passing the mixtures back and forth through the emulsifying needle. In the presence of elevated pressures, the emulsifying needle may become dislodged from one or both syringes, unintentionally, thereby compromising the preparation process.
Prior art arrangements suffer from another disadvantage in that the emulsifying needles, in order to reduce costs, include separable connectors for joinder to common, general purpose syringes. Thus, the arrangement does not provide a control to restrict the syringes which can be used in the process.
As a further drawback, the emulsifying needles require a fairly expensive construction since they utilize surgical stainless steel materials processed according to familiar standards required in the medical industry. The emulsifying needles present a substantial capital investment and hence are adapted for re-use, requiring an intervening cleaning and sterilization procedure, at a minimum. This accordingly presents questions of cross contamination or other questionable conditions, adding to the complexity of the work environment.
As an another drawback, the single emulsifying passageway (or single passage) emulsifying needles in the art require many iterative back and forth passes to achieve uniform mixing, especially for higher viscosity medicaments such as gels. This drawback may cause potential non-uniform multiple-dose medicament. Non-uniform multiple-dose medicament may pose risk to patients either by under- or over-dose.